Recovery of nicotine from dilute aqueous solutions



Sept. 1, 1964 R. M. NEEL 3,147,200

RECOVERY OF NICOTINE FROM DILUTE AQUEOUS SOLUTIONS THEREOF BY DISTILLATION Filed Dec. 28. 1961 REBOILER RECEIVER CONDENSER U F". 2 k I I- v [f -J fi N m 2 N o l- Bz.

5E6 CLILQ Q J N Q1 U J jg INVENTOR. 5 E ,PObePT/WJVeeL United States Patent 3,147,2tltl RECUVERY 0F NH CUTTNE TRQM DILUTE AQUE- UUS SQLUTKUNS THEREOF BY DTSTKLLATTQN Robert Monroe Neel, Winstomfilalem, N.C., assignor to R. .l'. Reynolds Tobacco Company, Winston-Salem,

N.C., a corporation of blew .lersey Filed Dec. 23, 1961, Ser. No. 162,866 3 Claims. (Cl. ZhZ-Sl) This invention relates to a process for recovering nicotine from dilute aqueous solutions thereof.

As is known, nicotine occurs in varying quantities in the leaf of the tobacco plant from which it can be volatilized using ammonia and steam. This process involves treating tobacco with ammonia in order to disengage the nicotine from the salts in which it is present in the tobacco by replacing it with ammonia. The free nicotine and ammonia are then removed from the tobacco with the aid of steam. The condensate resulting from this procedure comprises nicotine-water solutions in which the content of nicotine, while variable, is generally within the range from about 0.5 to 1.8%. Because of the commercial value of nicotine it is highly desirable that it be recovered from these condensate nicotine-water solutions. The recovery of nicotine from dilute aqueous solutions by simple distillation is complicated by the fact that upon distillation at atmospheric pressure a nicotine-water azeotrope is formed in which the maximum nicotine content is about 2.52 percent. Recovery of such an azeotrope by distillation at atmospheric pressure is not at all practical, the equilibrium vapor and liquid composition being substantially the same in the range from about 0 to 2.52 percent.

It is therefore one of the objects of this invention to provide a process whereby nicotine is efliciently recovered from dilute aqueous solutions by distillation.

The process of the present invention makes possible the recovery of nicotine from dilute aqueous solutions thereof without the use of solvents or other additives and with minimum waste disposal problems. When the process of the invention is employed to recover nicotine from dilute aqueous solutions containing ammonia, such as the condensate solutions resulting from tobacco denicotinizing operations, maximum recovery of the ammonia is also achieved.

in accordance with the present invention nicotine is recovered from dilute aqueous solutions thereof by a twostage distillation procedure, the first distillation being carried out at super-atmospheric pressures with the second distillation being carried out at sub-atmospheric pressures. More particularly, according to the present invention nicotine is recovered from dilute aqueous solutions such as the condensate solutions resulting from tobacco denicotinizing operations by distilling the aqueous solution at a pressure above atmospheric and preferably at pressures ranging from about 40 to 250 pounds per square inch absolute. The distillate resulting from the distillation at the preferred higher pressures comprises a water-nicotine azeotrope substantially enriched in nicotine content. This distillate is then subjected to a second distillation at a pressure no more than about 400 millimeters of mercury absolute, preferably from 100 to 400 millimeters of mercury absolute. At distillation pressures below about 400 millimeters of mercury absolute no water-nicotine azeotrope is formed, thereby permitting substantially complete separation of the nicotine from the water.

The process of the present invention is described in detail in conjunction with the accompanying drawing in which FIGURE 1 is a diagrammatic flow sheet illustrating one presently preferred embodiment of the invention.

Referring to FIGURE 1, a dilute aqueous solution which, for purposes of illustration, comprises the condensate from a tobacco denicotinizing operation, is intro- 3,147,200 Patented Sept. 1, 1964 duced into multiplate pressure fractionating column 10 through line 12 by means of pump 14. Fractionating column it? is preferably operated at pressures from about 40 to 250 pounds per square inch absolute and a temperature sufliciently high to distill the aqueous nicotine solution. Preferably, fractionating column 10 is operated in a temperature range from about 130 C. to 200 C. When fractionating column 10 is operated at the preferred operating conditions the dilute aqueous nicotine solution is fractionated to remove the nicotine and ammonia as overead. The overhead vapor from fractionating column 10 comprises a nicotine-water azeotrope substantially enriched in nicotine content, which, for example, may contain from 4 to 10 percent nicotine. This overhead is taken 0d via line 16 and passed to shell and tube heat exchanger 18 where it is condensed.

The heat exchanger 18 serves as a condenser for the overhead vapors from column lib and as an evaporator for the water in the bottoms from the column 10. The vapors enter the tube side of the heat exchanger through line 16 at the column operating pressure, but the water is allowed to partially flash into the shell side of the heat exchanger through a pressure reducing valve in line 26. Therefore, with the high pressure vapor in the tubes they are kept at a temperature of about 125 C. or higher, which is hot enough to convert the water in the underflow into steam for reuse in the denicotinizing operation. A small amount of water is bled oil from the shell side of the heat exchanger through line 19 in order to flush out any nonvolatiles entering the system.

Water plus traces of nicotine and non-volatile materials comprise the bottoms from the fractionating column 19, which are passed through line 20 to shell and tube reboiler 22 and through line 26 to heat exchanger 18. Steam at a pressure at least 50 pounds per square inch above column operating pressure is introduced via line 24 into reboiler 22 to vaporize a part of the bottoms, with the vapor being passed via line 2% to fractionating column 19 to supply heat thereto.

The condensate from heat exchanger 18 is passed through line 32 to receiver 36. A portion of this condensate is withdrawn at a point well above the bottom of 36 in order to take advantage of any separation of a high nicotine content phase which may occur near the surface. This portion, along with ammonia, is fed via linev 34 to multiplate fractional distillation column 44, which operates at sub-atmospheric pressures. The remainder, and larger portion, of the condensate is removed from the bottom of the receiver through line 38 by pump 40 and returned to the top of column 10 as reflux. The top of distillation column 44 is operated in a temperature range from about 50 to C. depending upon the pressure used, and a sub-atmospheric pressure of from about 100 to 200 millimeters of mercury absolute. Nicotine in a concentration from about to about percent is removed as underflow from column 44 and circulated through line 46 to reboiler 48 while some is bled off by pump 42 as product through line 50.

The overhead from strippingcolumn 44 comprising ammonia and water vapor and minor or trace amounts of nicotine is passed via line 52 to condenser 54 which is operated in a temperature range from about 5065 C., which is sufliciently low to condense the water while permitting a major portion of the ammonia to escape as a vapor through line 56. The water condensate from condenser 54 is divided, and one part is returned via line 58 to the top of column 44 as reflux. The remainder of this condensate is recycled by means of pump 60 through line 62 to fractionating column 10. The ammonia leaving condenser 54 via line 56 to vacuum pump 57 can be recovered for further use.

The following description and results relate to three experimental runs wherein dilute aqueous nicotine solutions were distilled at a pressure of about 95 pounds per square inch absolute and a temperature of about 155 161 C. The charge solution in each instance was either a nicotine-water solution or a condensate resulting from a tobacco denicotinizing operation which contained Water, ammonia and nicotine plus traces of other tobacco constituents. All of these runs were made utilizing from 2200 to 2500 milliliters of the charge solution which were introduced into a distillation apparatus and heated until all air and a large part of ammonia was vented from the system and refluxing began. All runs were made With about the same heat input, and total boil-up at the pressure of 95 pounds per square inch absolute was about 14 milliliters per minute measured as overhead condensate. After distilling under total reflux for one to two hours product take-off was initiated at a rate which usually varied from about 0.5 to 0.7 milliliter per minute. This resulted in a reflux to product ratio between 19:1 and 27: 1.

Run #1 was made, starting with a 1.04 percent nicotine solution as charge Without any ammonia present. A 10.8 percent nicotine content overhead vapor sample was obtained after total reflux and a 7.1 percent nicotine content sample was taken continuously as reboiler nicotine content dropped to 0.31 percent.

Run #2 was made using as a charge an aged condensate resulting from denicotinization of burley tobacco. The charge contained 0.69 percent ammonia and 0.98 percent nicotine. Fractionating results were then very similar to those of run #1 except that the first 50 milliliters of overhead vapor condensate contained 2.8 percent ammonia as well as 7.7 percent nicotine.

In run #3 a fresh condensate resulting from a tobacco denicotinizing operation Was used as charge. Results were similar to those of runs #1 and #2. The extraction and titration method of Cundiff, R. H. and Markunas, P. C. described in the Journal of Analytical Chemistry 27, p. 1650-1654 (1955) was used for all nicotine analyses.

The conditions used and analytical results from all three runs are summarized below in Table I.

TABLE I Data at 95 p.s.i.a. Nominal Pressure [Pot and overhead vapor temperatures 155-161 C. (BU-322 F.) range; condensate 100-155 C. (212311 F.) range] Run No 1. 1 2 3 Charge Used:

Source Synthetic--. Aged Denico- Fresh Denietinizer Conotinizer densate. Condensate. Nicotine (pereent)- 0.98 0.84. NHs (percent) 0.69 1.17. Volume (ml.) 2,500 2,500. Time on Total Reflux 253 .203.

(min). Time on Take 011 (min). 160 187. Sample Analyses (percent Nie.): Time from Start of Reflux- 90 min 5.9.

103-110 min 120-140 min 0.29 5.3". 227-238 min 13.6. 241-255 min. 320-3381uin- 8.8 0111). 355-365 min. 0.07 0100). 373-391 min. 0. 07 410-422 min 0.21 7.6

B=Bottoms; V=Overhead vapor; R=Reflux or product; A: Ammonia.

As is seen from the above data, distillation of the dilute aqueous nicotine solutions at the high pressures results in condensates substantially enriched in nicotine content.

Analysis of the distillate from the sub-atmospheric distillation shows that the composition of the nicotine-water azeotrope decreases in nicotine content as indicated in Table II below.

400 mm. Hg abs. (1)

Vapor equilibrium data obtained at 200 mm. Hg abs. at

temperatures of 68 C. 18 as follows:

Liquid in Vapor Pot, Condensate, percent percent Nicotine Nicotine The above data demonstrates that by distillation at a pressure of 200 mm. Hg absolute or less Water and nicotine can be efiiciently separated with water being removed as distillate and nicotine in concentrations of from about 90 percent to 100 percent removed as bottoms.

Those modifications and equivalents which fall within the spirit of the invention and the scope of the appended claims are to be considered part of the invention.

I claim:

1. In a process for recovering nicotine from dilute aqueous solutions thereof by distilling the said solution, the improvement which consists of first distilling said aqueous nicotine solution at a pressure within the range from about to 250 pounds per square inch absolute to obtain a nicotine enriched distillate, and then distilling said distillate at a pressure from about 100 to 300 millimeters of mercury absolute to obtain a highly enriched nicotine residual liquor.

2. A process for recovering nicotine from a dilute aqueous ammoniacal solution thereof which comprises distilling said nicotine solution at a pressure in the range 40 to 250 pounds per square inch absolute to obtain a nicotine enriched distillate, condensing vapor obtained from said distillation, returning a portion of said condensate to the super-atmospheric pressure distillation operation as reflux, distilling remainder of condensate and ammonia vapor at a pressure of not more than about 400 0 millimeters of mercury absolute to obtain a bottom fraction of high nicotine content and an overhead fraction containing Water and ammonia and separating ammonia as a vapor by condensation of the water.

3. In a process for recovering nicotine from dilute aqueous solutions thereof by distilling the said solution, the improvement which consists of first distilling said aqueous nicotine solution at a pressure within the range from about 40 to 250 pounds per square inch absolute to obtain a nicotine enriched distillate, and then distilling said distillate at a pressure of about 200 millimeters of mercury absolute to obtain a highly enriched nicotine residual liquor.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Bulletin De La Soc. Chem; M.D.E., Tsakalotas, France (1909) (pages 397-404).

Azeotropie Data; Horsely, June 1952; American Chem. Soc., Washington, DC. (pages 318-328 cited).

UNITED STATES-PATENT? OFFICE? CERTIFICATE OF CORRECTION Patent No, 3 147,200 September 1, 1964 Robert Monroe Neel It is hereby certified that err or appears in the above 'n'umbered' patent' 'equiring correction and that th e said Letters Patent'shouldread ascorreeted below Column l before line 10,

the following footnote should be inserted:

Azeotr-ope disappears,

Signed and sealed this 15th day of December 1964,

(Sam) Attesti I Commissioner of Patents 

1. IN A PROCESS FOR RECOVERING NICOTINE FROM DILUTE AQUEOUS SOLUTIONS THEREOF BY DISTILLING THE SAID SOLUTION, THE IMPROVEMENT WHICH CONSISTS OF FIRST DISTILLING SAID AQUEOUS NICOTINE SOLUTION AT A PRESSUR WITHIN THE RANGE FROM ABOUT 40 TO 250 POUNDS PER SQUARE INCH ABSOLUTE TO OBTAIN A NICOTINE ENRICHED DISTILLATE, AND THEN DISTILLING SAID DISTILLATE AT A PRESSURE FROM ABOUT 100 TO 300 MILLIMETERS OF MERCURY ABSOLUTE TO OBTAIN A HIGHLY ENRICHED NICOTINE RESIDUAL LIQUOR. 